Propeller for operation in air



I E. w. BOWEN. PROPELLER FOR OPERATION IN MR,

APkUCATiON HLED AUG-I2. l9l9 Patented Feb. 24, L920.

2 SHEETS-SHEET E E. W. BOWEN,

PROPELLEB FOR OPERATION IN AIR. APPLICATION FILED nut-1.12. 1919.

1,331,612. Patented Feb. 24,1920.

- 2 SHEETS-SHEET 2.

- UNITED STATES PATENT OFFICE.

ERNEST wnmson rowan, or sunnnr, ENGLAND, nssrenon or rma'rr-rrvn ran cam. r0 rrtorus LEWIS navms, or LONDON, ENGLAND.

PBOPELIEBIOB OPERATION IN All.

Specification of Letters Patent.

Patented Feb. 24, 1920.

Application filed August 12, 1919. Serial No. 317,053.

certain new and useful Improvements 111' Propellers for Operation in Air, "of which the following is a specification.

This invention relates to propellers for operation in air, and isparticularly' applicable to propellers for aeroplanes.

Wooden air-screws as now used deteriorate somewhat rapidly and whip ing'of the blade occurs when driving, wh

ablade broken off, the machine driven by it becomes unmanageable.

.A primary object ofthis invention is to provide an air-screw to which thesedefects are not attached, and which for a given weight shall be mechanically stronger than those at present in use,and shall retain its true form and pitch under full load conditions.

Another object is to provide an air-screw blade consisting solely of a cellular metal structure, and an air-screw blade to be built up by welding together a number of steel pressings.

A still further object is to facilitate the construction of blades comprising a cellular metal structure by bending the edges of the longitudinal driving .members' t ereof to correspond to the shape of the-two operative faces of the blade, so that when these membersare connected together either directly, say by welding, or indirectly, say by means of sheet-metal or wood secured to them, a blade of the required contour shall be readily obtained.

Previous constructions of air-screws have been proposed wherein a plurality of ribs were used which extended longitudinally through each blade, each rib being secured, along its two lateral edges, to outer members,'which members constituted the driving faces of the blade, and wherein a number of ribs were disposed transversely across the blade; another construction employed in each blade was a single longitudinal strengthening rib whose root was welded to th boss and situated in a plane the passing through or approximately through axis of the said boss.

The present invention consists in the construction, arrangement and combination of ich sometimes results in fracture at the root;"with a further object is to enable parts described hereinafter and pointed out in the claims.

One embodiment of the invention and several modifications thereof are diagrammatically illustrated .by way of example in the accompanying'drawings wherein- Figure 1 ls'an elevation showing an airscrew according to the invention, part ofone blade bein shown broken away,

Fig. 1 is a etail plan view of the boss of the propeller whereon are welded driving arms shown broken away, and

Fig. 2 comprises cross-sections a, b, c, d, e and 1 taken, respectively, on the lines lettered correspondingly in Fig. 1;

Fig. '3 is a detail cross-sectional view showing a modified form of driving arm of l in air-screw blade according to the inventlon; v

Fig. 4 is a cross-section of a modified form of blade according to the invention;

Fig. 5 is a detail view showing another form of driving arm; 7

Fig. 6 is an elevation showing part of an air-screw according to the invention comprising reinforced wooden blades, and

7 comprises cross-sections g, h, i, k on the lines let tered correspondmgly in 6. Like reference letters designate corre' sponding parts in all the views. Referring first to Figs. 1, 1 and 2, a boss Aof a pro lleris constituted by a flanged steel sleeve aving its axis of rotation at A. Each blade comprises three driving-arms B that are welded at one end to the boss A and extend outward approximately arallel to one another to the tip of the b ade. The two lateral edges of each of these drivingarms B are turned one in one direction, and the other in the opposite direction to constitute flangesB}, B shaped each in conformity with the required exterior contour of the (parts of the blade at whicl? they are situate A steel plate erative driving to the flanges B and to one of the flanges A" on the ends of the boss A, and a second steel plate C shaped to form the other operative driving face of the blade is welded to the flanges B and to the other flange on the ooss A. The edges ofthese two shell plates C, C met all around the blade except where they embrace the boss C shaped to form the one OP- face of the blade is welded A and are secured together by welding along the leadin edge, and along the trailin edge of the bla e, as indicated in Fig. 2 at 2 and C and also at the tip of the blade. If desired, these plates and also the driving-arms may diminish inthickness from the root to the tip of the blade. The joints at the edges of the plates may be butt or lap welded; if they are lap welded the two edges of the plates are preferably each reduced in thickness before being welded so as top'rovide a smooth joint.

The driving arms have their roots disposed each in a plane transverse to the axis of the boss as clearly shown in Fig.1, and are then'twisted more and more out of these planes the nearer they approach to the tip of the blade as will. be understood from Figs. 1 and 2. Also, as clearly shown in these figures, each driving arm is widest near the boss and becomes gradually narrower toward the tip of the blade.

Preferably, two blades on opposite sides of the boss are made integral one with the other. In this case, two corresponding driving arms, one for each blade are made by pressing them in one piece of the required shape out of sheet steel, a hole being formed between the two arms in the middle of the pressing whereupon, the two arms integral one with the other are threaded on to the boss and welded thereon. Any desired number of driving arms B for two opposite blades may be provided at any convenient distance apart in this manner. The steel plates C for the two blades are likewise made integral one with the other, as also are the plates C and these plates each extending from tip to tip of the blades are welded one to the other at their edges and I to the boss, as described above with reference to Flgs. 1 and 2.

It will be seen that each blade made as described above is of similar structure and of great strength for a given weight; Such a blade is adapted to retain its true form and pitch under full load conditions,- and will also largely absorb vibration without resultant fatlgue and without consequent permanent deformation,

As shown in Fig- 3, the web of the driv- I ing arm B is corrugated, whereby the arm is rendered stiffer longitudinally than a similar arm having a flat web.

An air-screw according to the invention whereof each blade comprises sheet metal driving-arms may be built up without using separate shell plates as described above shaped to the exterior contour of the blade and mounted on the driving arms, but by welding the flanges of one driving-arm d1- rectly to those of the next, welding together the two flanges to one outer driving-arm at the leading or trailing edge of the blade, and shaping the other outer driving=arm to vided. The two flanges B, B of the one outermost arm shown at the left hand of Fig. 4 are welded together at their lateral edges to form-the trailing edge of the blade, while the other outermost arm shown at the right hand of the figure is shaped to con stitute the leading edge and is not provided with the above-mentioned shoulders. At the root of the blade these driving arms may be nested more completely one into another than is shown in the figure, and threaded on to a sleeve forming the boss, as described above, the whole being welded into a continuous, light and rigid cellular structure.

Fig. 5 is a perspective view showing a driving-arm B having castellated flanges some parts of which are turned in one direction and alternate parts in opposite directions. This form of driving-arm may be employed in a manner similar to that described above in reference to F i 'sl, l and 2. Referring to Figs. 6 and 7, the boss A has a hollow radial arm A into which is socketed the root of a wooden blade reinforced with metal driving-arms B of the kind described above with reference to Figs. 1, 1 and 2. In this blade the driving-arms B are welded in the arm A their flanges ,do not carry shell plates C,- C alon their entire length, however, but only at t e root end of the blade. The root of the blade is thus a tubular structure whereof two plates C, C constitute the periphery of the desired exterior shape, and wherein are fixed pieces 'of timber D which extend to the tip of the blade. The pieces of wood D are shaped each tothe required exterior contour of the portionof the blade which they form, and the flanges or the turnededges of the driving-arms D- at the air-propelling faces of the blade are let into. the pieces of wood D so that the outer face of each flange is flush with the adjacent faces of the pieces of wood D. Pegs E are used in the usual manner for securmg together the pieces of wood D and the drivlng-arms B.

One advantage of the mode of constructing wooden blades as described above with reference to Figs. 6' and 7 isthat it enables much shorter pieces of timber to be used than those required heretofore for building propellers of a corresponding size. Consequently considerable economy of material is effected.

It will be appreciated that each cell or I the blade, and that the driving-arms one "driving-arms that are disposed approximately parallel to one another with their edges shaped to conform to the two operative faces of the blade, are fixed to the boss, extend therefrom toward the tip of the blade, and have their roots disposed in planes transverse to the axis of the boss and spaced relatively to one another along the boss in the axial direction thereof.

2. In an air-screw, the combination with driving-arms. that are disposed approximately parallel to one another with their edges shaped to conform to the two operative faces of the blade, are fixed to the boss, extend therefrom toward the tip of the blade, and have their roots disposed in planes transverse to the axis of the boss and spaced relatively to one another along the boss 1n thefaxial direction thereof, and

means shaped to the required exterior contour of the blade carried by the drivingarms.

3. In an air-screw, the combination with a metal boss, of a blade carried thereby, which blade comprises a plurality of metal driving-arms that are disposed approximately parallel to one another with their edges turned over to conform to the required exterior contour of the blade, are fixed to the boss, extend therefrom toward the tip of the blade, and have their roots disposed in planes transverse to the axis of the boss and spaced relatively to one another along the boss in the axial direction thereof, and sheet-metal shaped to the required exterior contour of the blade rigi y secured to the edges of the driving-arms.

4. In an air-screw, the combination with a metal boss, of a blade carried thereby, which blade comprises a plurality of metal driving-arms that are disposed approximately parallel to one'another with both their longitudinal edges shaped to conform to the two operative faces of the blade, are fixed to the boss, extend therefrom toward the tip of the blade, and have their roots disposed in planes transverse to the axis of i the boss and spaced relatively to one another along the boss in the axial direction thereof, and two sheet-metal plates shaped each to conform to an operative face of the blade and rigidly secured to the said edges of the driving-arms on opposite sides of the latter and welded together at their abutting edges.

on and secured to the boss, extend there-v from toward the tip of each blade, and have their roots disposed in planes transverse to the axis of the boss and spaced relatively to one another along the boss in the axial di rection thereof.

6. An air-screw blade having a cellular metal structure which comprises a plurality of metal driving-arms that are disposed approximately parallel to one another with their edges turned to conform to the two operative faces of the blade, extend from the root toward the tip of the blade, and have their roots disposed in planes transverse to the axis of rotation of the blade and spaced relatively to one another along the said axis.

7. An air-screw blade having a cellular metal structure which comprises a plurality of metal driving-arms that are disposed aptheir edges turned to conform to the two operative facesof the blade, extend from the root toward the tip of the blade, and have their roots disposed in planes transverse to the axis of rotation of the blade and spaced relatively to one another along the sald axis and sheet-metal shaped to therequired exterior contour of the blade rigidly secured to the shaped edges of the driving-arms v 8.'An.-air-screw blade having a cellular metal structure which comprises a plurality of corrugated metal driving-arms that are disposed approximately parallel-to'one another with their edges turned'to conform to the two operative faces of the blade, extend from the root toward the tip of the blade, and have their roots disposed in planes transverse to the axis of rotation of the blade and spaced relatively to one another along the said axis.

In testimony whereof I aflix my signature.

ERNEST WINDSOR BOWEN. 

